Improvement in yields for semiconductor devices is a continuous goal. One area that may be improved is the unintentional implanting of particles into the workpiece. In traditional beam line ion implantation equipment, electrical and magnetic fields are used to control the velocity and trajectory of ions as the ions travel through the system. For example, ions that do not have the desired mass/charge ratio may be screened before these unwanted ions implant the workpiece.
However, neutral particles, or particles with negative charge, are oblivious to or not effectively controlled by, these fields, and therefore cannot be controlled using traditional techniques. Consequently, these neutral or negatively charged particles may be transported through an ion beam line, and may be implanted in the workpiece, resulting in damage to devices and yield loss. These neutral particles may be caused by sputtering of the equipment in the beam line.
Conventional approaches to the issue of particle contamination have been to attempt to reduce the generation of these particles. For example, liners may be installed in the path of the beam to minimize sputtering. Additionally, these liners may be constructed from graphite, because of the assumption that carbon particles are not detrimental, or are less detrimental, to the workpiece. However, eliminating all particles may not be feasible, or even possible.
Therefore, an apparatus that can reduce the number of particles that impact a workpiece would be beneficial. Further, it would be advantageous if the apparatus cooperated with the existing techniques and mechanisms for controlling the velocity and trajectory of ions to be implanted.